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MySQL 5.7 Reference Manual  /  ...  /  The Password Validation Plugin

6.5.3 The Password Validation Plugin

The validate_password plugin serves to test passwords and improve security. The plugin exposes a set of system variables that enable you to define password policy.

The validate_password plugin implements these capabilities:

  • In SQL statements that assign a password supplied as a cleartext value, the plugin checks the password against the current password policy and rejects the password if it is weak (the statement returns an ER_NOT_VALID_PASSWORD error). This applies to the ALTER USER, CREATE USER, GRANT, and SET PASSWORD statements, and passwords given as arguments to the PASSWORD() and OLD_PASSWORD() functions.

  • The VALIDATE_PASSWORD_STRENGTH() SQL function assesses the strength of potential passwords. The function takes a password argument and returns an integer from 0 (weak) to 100 (strong).

For example, validate_password checks the cleartext password in the following statement. Under the default password policy, which requires passwords to be at least 8 characters long, the password is weak and the statement produces an error:

mysql> ALTER USER USER() IDENTIFIED BY 'abc';
ERROR 1819 (HY000): Your password does not satisfy the current
policy requirements

Passwords specified as hashed values are not checked because the original password value is not available for checking:

mysql> ALTER USER 'jeffrey'@'localhost'
       IDENTIFIED WITH mysql_native_password
       AS '*0D3CED9BEC10A777AEC23CCC353A8C08A633045E';
Query OK, 0 rows affected (0.01 sec)

To configure password checking, modify the system variables having names of the form validate_password_xxx; these are the parameters that control password policy. See Section 6.5.3.2, “Password Validation Plugin Options and Variables”.

If validate_password is not installed, the validate_password_xxx system variables are not available, passwords in statements are not checked, and the VALIDATE_PASSWORD_STRENGTH() function always returns 0. For example, without the plugin installed, accounts can be assigned passwords shorter than 8 characters.

Assuming that validate_password is installed, it implements three levels of password checking: LOW, MEDIUM, and STRONG. The default is MEDIUM; to change this, modify the value of validate_password_policy. The policies implement increasingly strict password tests. The following descriptions refer to default parameter values, which can be modified by changing the appropriate system variables.

In addition, as of MySQL 5.7.15, validate_password supports the capability of rejecting passwords that match the user name part of the effective user account for the current session, either forward or in reverse. To provide control over this capability, validate_password exposes a validate_password_check_user_name system variable, which is enabled by default.


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